VR-FOCUS: evaluating eye tracking during a virtual reality N-back task as a marker of cognitive load in chronic pain

Immersive virtual reality (VR) is a promising medium for adaptive pain therapeutics, but objective markers of cognitive load suitable for real-time adaptation remain insufficiently characterised in chronic pain. This study evaluated whether eye tracking embedded within a consumer-available VR system provides signatures of cognitive load during a VR N-back task. A total of 84 participants (42 healthy controls, 42 chronic musculoskeletal pain) completed five levels (Baseline to 4-Back) while ocular responses were recorded.

Performance declined and subjective workload increased with task level, confirming successful manipulation of cognitive demand, although performance plateaued beyond 3-Back. In mixed-effects models, larger pupil diameter and higher blink rate were associated with task level and workload, without group differences. Logistic regression using summary features discriminated 1-Back from 4-Back at near-chance levels (0.51–0.60).

Time-series classifiers exploiting temporal structure performed substantially better in healthy controls (0.74–0.88) but were attenuated in chronic pain (0.58–0.65). Age alone did not appear to explain this difference, although a contribution cannot be excluded. These findings support the feasibility of VR-embedded eye tracking for cognitive load estimation in healthy adults, but performance in chronic pain is currently insufficient for reliable individual-level inference; closed-loop application in this population will require participant-calibrated models and prospective validation.

This work was completed as part of J.T.’s PhD programme and was supported by funding from the University of East Anglia and Revolve Labs Ltd. Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, UK Jordan Tsigarides, Jennifer O. Bowler, Jack Dainty & Alexander Macgregor Department of Computing Science, University of Southampton, Southampton, UK J.T. holds a Chief Medical Officer role at Revolve Labs Ltd.

Revolve Labs Ltd provided financial support for J.T.’s PhD programme during which this study was conducted. The company had no role in the study design, data collection, analysis, interpretation, manuscript preparation, or decision to submit for publication. The other authors declare no competing interests.

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